CRYSTALLOIDS. 



51 



weak skeleton with firmer skin remains behind. The crystalloids in the endosperm -cells 

 of Ricinus communis are, like all crystalloids, insoluble in water, and are very conspi- 

 cuous when thin sections of the tissue are laid in water, which destroys the structures 

 surrounding the crystalloid, and sets it free. They frequently take the form of octo- 

 hedra or tetrahedra, less frequently of rhombohedra ; but the system is not certainly 

 determined. The crystalloids of colouring matter were first detected by Nageli in 

 an imperfect form in the petals of Viola tricolor and Orchis, better developed in the 

 dried fruits of Solarium americanum ; in the latter case they form in the large cells of 

 the flesh of the fruit clusters of a deep violet colour ; the separate crystalloids are thin 

 plates, single regular rhombs, often with truncated angles, &c. According to Nageli it 

 does not admit of a doubt that the crystalline form is the rhombic prism in a very abbre- 

 viated tabular shape ; the hexagonal tables are composed of six simple ones. In pure 

 water they remain unchanged ; alcohol extracts the colouring matter, as also do dilute 

 acids ; both leave, after long treatment, a verv weak skeleton which is capable of swell- 

 ing, while the whole crystal does not swell ; Nageli states that the crystalloid consists 

 of a very small quantity of albuminous and a large quantity of another substance, with 

 some colouring matter. 



Crystalloids of albuminous substance have also been found in red marine Algae 

 (Florideae) and in one Fungus. Cramer observed the first case of this kind ; in specimens 

 of the Floridea Bornetia seciindijlora which had lain a long while in solution of sodium- 

 chloride, as well as in specimens prepared in alcohol of Callithamnion caudatum and semi- 

 nudum he found hexagonal plates and prisms with all the properties of crystalloids, and 

 coloured red by the expelled colouring matters of the Algae. They were found in the 

 vegetative cells as well as in the spores. In sodium-chloride preparations of Bornetia 

 octohedral crystalloids were found also, apparently belonging to the klino-rhomblc 

 system ; they were colourless. In living plants of the same Alga, Cohn also dicovered 

 colourless octohedral crystalloids which absorb the red colouring matter expelled from 

 the pigment-grains. Within and without the cells of Ceramium rubrum preserved in 

 sea-water with glycerine, klino-rhombic prisms formed, coloured red by the expelled 

 pigment; they are clearly similar to the hexagonal crystalloids first observed by Cramer 

 which appeared only after death, while the colourless octohedra are to be found in the 

 living cells. Finally, in dried specimens of other Florideae, Griffithsia harhata, G. nea- 

 politana, Gongoceros pellucidum, Callithamnion seminudum, Klein observed colourless, 

 crystalloids of a different form. These formations may all be comprised in the name 

 first given by Cramer, — Rhodospermine. In the sporangiferous filaments of'Pilobolus, 

 Klein found also colourless octohedra of tolerably regular structure with the properties 

 of crystalloids described above. 



Sect. 8. Grains of Aleurone (Proteine-grains^). — The reservoirs of 

 ripe seeds, i. e. the endosperm and the cotyledons of the embryo, always contain 



^ These structures were discovered by Hartig (Bot. Zeitg. p. 881, 1855), and described in detail 

 but imperfectly (ibid. p. 257, 1856); further observations were furnished by Holle (Neues Jahrb. der 

 Pharmacie, Bd. X, 1858) and Maschke (Bot. Zeitg. 1859). All these observations left undecided the 

 relationship of the grains to the surrounding matrix ; it appeared in particular to be assumed that 

 in oily seeds the latter consists of oil only. In the first and second editions of this book I op- 

 posed this view, and pointed out that the matrix in the cells of oily seeds consists of a mixture 

 of oil and albuminoids, or rather, of a very oily protoplasm ; on the other hand I fell into the 

 error, partly in consequence of the use of diluted ether, of considering the aleurone-grains them- 

 selves as a compound of albuminoids and oil. This error has been refuted by Dr. Pfeffer's recent 

 researches. This very careful investigation was commenced in the Wiirzburg laboratory, where 

 I had the opportunity of seeing numerous preparations which were decisive as to the principal 

 question. Dr. Pfeffer had the kindness to communicate to me, before going to press, a detailed 



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